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00:00Since the dawn of civilization, humans have been constantly pushing the limits of science forward.
00:06But despite our insatiable thirst for knowledge,
00:09there are mysteries that still baffle even the brightest of minds.
00:13From the origin of the universe to the perplexing nature of consciousness itself,
00:18science is abundant with profound puzzles.
00:22This is Unveiled, and today we're taking a closer look at
00:2610 massive questions that science still can't answer.
00:31Do you need the big questions answered? Are you constantly curious?
00:34Then why not subscribe to Unveiled for more clips like this one?
00:37And ring the bell for more thought-provoking content!
00:401. What is the universe's origin?
00:44A great deal of effort has been put into answering our first big question,
00:48resulting in a wide choice of scientific explanations and suggestions to choose from…
00:53but still, many feel that we may never know with absolute certainty.
00:57The most widely accepted answer is, of course, the Big Bang Theory,
01:00which claims that the universe began 13.8 billion years ago,
01:04when it burst forth from an extremely hot singularity.
01:08A singularity is an infinitely small point of infinite density which, so the theory says,
01:14contained the entire matter of the universe, before it all rushed outwards.
01:18Singularities don't exactly represent anything physical, though,
01:22and are instead a mathematical phenomenon.
01:25That means that inside them, we know that physics breaks down.
01:29Nevertheless, the Big Bang Theory says that that is where we came from…
01:33and that in the first second of the universe, this point of infinite density exploded,
01:38and the cosmos underwent a period of exponential growth called inflation.
01:43Initially, it all happened at beyond the speed of light,
01:46before the rush of immense energy eventually cooled.
01:49Once temperatures dropped, atoms and particles managed to form,
01:53later forming stars, galaxies, and the entire structure of what we now know as the universe.
02:00While it's a widely accepted theory, it does leave some questions unanswered,
02:05and so a great deal of alternatives exist.
02:08One example is broadly known as Cosmic Inflation,
02:11an idea that would be viewed as an extension of the Big Bang.
02:15It explains the expansion of the universe in greater detail,
02:18and matches up with observational evidence…
02:21but it doesn't really address exactly what started it, what drives it, or how it will end.
02:27More radical alternatives include String Gas Cosmology,
02:31which proposes that the universe began as a box of quantum strings,
02:35the tiniest states of matter possible, in thermal equilibrium.
02:39If the box of strings were true, it would bypass all the problems that a singularity throws up…
02:45but the problem is that string theory in general is currently unproven.
02:50Number two, what is the fate of the universe?
02:53Moving to the other end of the timeline, how the universe will end is perhaps even more difficult to know.
02:59Currently, our universe is observed to be expanding at an accelerated rate,
03:04and we believe this to be happening due to dark energy,
03:07which makes up roughly 70% of the cosmos.
03:10But, unfortunately, that's pretty much all we know about this mysterious force.
03:15Even so, the result is that everything in the universe, from planets to stars to galaxies,
03:20is getting further and further apart.
03:23Eventually, in one version of events at least, the stars will exhaust their nuclear fuel,
03:28and the cosmos will fade into darkness.
03:30Even black holes will evaporate due to Hawking radiation,
03:34leaving a dark cosmos behind, in a bleak scenario called heat death.
03:39But, actually, there are other theories as to the universe's fate as well.
03:43Since we don't understand the nature of dark energy, things could indeed go differently.
03:48The Big Crunch Theory wonders if universal acceleration could instead reverse someday,
03:53causing the entire cosmos to gravitationally collapse.
03:57The end result here would be everything we know spiralling back down into an extremely dense, hot state.
04:03Into a new singularity.
04:05It could end there, or it could potentially lead to another Big Bang.
04:09This more cyclic model gives our universe a poetic end and new beginning,
04:14with the cosmos infinitely repeating itself for eternity.
04:18It's often referred to as the Big Bounce.
04:21Finally, though, the Big Rip Theory presents a different and more horrifying story.
04:26It predicts that the ever-unknowable dark energy will actually grow stronger over time,
04:32and will eventually overcome all other forces.
04:35In this, frankly, catastrophic scenario, the increased dark energy will tear apart galaxies,
04:41stars, planets, and the entire fabric of space-time.
04:45Overall, the heat death scenario we started with is the most favoured among contemporary scientists,
04:51but it's also certainly unclear precisely how dark energy might evolve in the future,
04:57so nothing is truly off the table.
04:59Number 3. What are dark matter and dark energy?
05:03So, we don't understand 70% of nature.
05:06What about the other 30%?
05:08Well, the sober reality is that only 5% of that is regular, observable matter.
05:13The other 25% is dark matter.
05:16So, what are both dark matter and dark energy?
05:19Despite making up approximately 95% of the universe, we have little to no idea as to their nature.
05:26Combined, they could reasonably be labelled as the most intriguing and mysterious components of the universe.
05:32Dark matter is unlike ordinary matter because it doesn't emit, absorb, or reflect any light.
05:38As such, it is completely invisible to light.
05:41We only know it exists thanks to the indirect gravitational effects that it has on cosmological objects, such as galaxies.
05:49We can view them from afar, observe how they behave,
05:53and we know that there must be a massive amount of mysterious, unseen mass that's orchestrating what we see.
05:59That mass is dark matter.
06:01We also have the phenomenon of gravitational lensing.
06:04This is a peculiar effect that occurs when light from distant objects is bent by massive, often invisible matter.
06:11Again, in many cases, it's dark matter that's to blame.
06:15Dark energy, the more dominant of the two, is arguably even more mysterious.
06:20We chiefly discovered it via observations of supernovae, which first revealed the universe's expansion.
06:26The most widely accepted suggested explanation is that dark energy is a hidden, repulsive force
06:32that's forever working to counteract gravity on the grandest of scales.
06:36We can find evidence of it via the energy density of space, as well.
06:41As the universe grows, matter dilutes, but the energy density remains constant.
06:46The answer? Dark energy.
06:48The reason? We just don't know.
06:51Number 4. Why is there a matter-antimatter imbalance?
06:55As it turns out, regular matter is also pretty perplexing.
06:59Specifically, it's uncertain why matter dominates over antimatter in our universe.
07:04According to the Standard Model, there should be an equal amount of matter and antimatter in existence.
07:10But, in reality, this isn't the case.
07:12So, why is there an imbalance between the two?
07:14It's one of the greatest challenges in physics, and it's known as the matter asymmetry problem.
07:19To scale it back, antimatter is composed of antiparticles,
07:23which are the counterparts to ordinary matter particles, such as electrons and protons.
07:28For every one of these, there is a corresponding antiparticle, with the same mass but opposite electric charge.
07:34For instance, an electron's antimatter counterpart is the positron.
07:39When a particle and its corresponding antiparticle meet, they annihilate,
07:43leaving behind gamma-ray energy.
07:45This much we know, but finding antimatter in significant quantities is a rare occurrence,
07:51and that's a little strange.
07:53If the Standard Model is correct, the Big Bang should have produced equal types of matter.
07:58The result would have been a universe filled entirely with radiation only.
08:02No complex structures would form, such as galaxies, stars, planets, and life.
08:07Thankfully, this isn't the case.
08:09Matter won out, and we're here to tell the tale,
08:12but discovering why that is, is crucial to our understanding of the cosmos.
08:17One possible explanation lies in what's known as charge parity, or CP violation.
08:23Violation is the key word here, as experiments have shown that some weak nuclear interactions
08:28violate the symmetry that theoretically should exist between matter and antimatter.
08:33It's argued that an early series of CP-violating processes in the universe
08:38are what led to a tiny imbalance,
08:40which eventually snowballed into the matter-dominated cosmos we have today.
08:45Another theory is baryogenesis, which proposes mechanisms where baryons,
08:50particles of regular matter like protons and neutrons, came to dominate anti-baryons.
08:56The exact details are largely unknown, and there are several different models for this,
09:01but again, researchers believe that it could explain the fundamental issue with the matter-antimatter split.
09:07Nobody knows for sure, though, and it's a puzzle that looks set to continue long into the future.
09:13Number 5. Is time travel possible?
09:16Of course, time travel has long fascinated humanity,
09:19inspiring countless science fiction stories in particular over the last century or so.
09:25But is it, will it ever be, really possible?
09:28The first and most often retorted answer is that actually we all travel in time every day,
09:33at a menial rate of one second per second.
09:36But that's not exactly… satisfying.
09:39What we're really asking is, can that rate be altered?
09:42Could we ever travel to anywhere that's not just incrementally into the future at the standard speed?
09:48Albert Einstein's general relativity does provide some options.
09:52According to the theory, massive objects cause a curvature in spacetime, which we perceive as gravity.
09:59This curvature affects the flow of time, though, which is a phenomenon called time dilation.
10:04Among many other things, it means that astronauts aboard the International Space Station
10:09already experience time as ever-so-slightly slower compared to people on Earth,
10:15due to the shifts in gravity and velocity on the ISS.
10:19It all amounts to a scientifically proven manner of moving into the future at a different rate,
10:24otherwise known as time travelling.
10:26It's extremely limited, though, it requires difficult conditions,
10:31and you're still only ever going forward, not backwards.
10:34For many, it could never translate into true time travel as science fiction depicts it.
10:40If we were trying to strongman our way to a more impressive result, we have wormholes,
10:45which relativity does again allow for.
10:48These are hypothetical tunnels through spacetime that, if traversable,
10:52could enable time travel reasonably easily.
10:55Unfortunately, however, there is zero evidence of wormholes in reality.
10:59And even if we had observed them, then it's predicted that they'd be extremely difficult to stabilize
11:04and perhaps impossible to ever travel through.
11:07As things stand, then, time travel is a complete impossibility.
11:11And it's a logical nightmare to boot, with variously infamous paradoxes
11:16such as the Grandfather Paradox ready and waiting to entangle anyone that ever did manage to achieve it.
11:22Number Six. What is Consciousness?
11:25One of the most elusive phenomenon ever observed is consciousness.
11:29We all experience it, but what exactly is it?
11:32It's an age-old question.
11:34It's generally described as the state of being aware of and able to comprehend our existence, thoughts, and surroundings.
11:41It's central to the human experience, turning us into sentient beings,
11:45capable of introspection, imagination, and intricate decision-making.
11:50It lets us perceive the world, form memories of it, and maintain a continuous personal identity.
11:56Take it away and we'd be… well, we wouldn't be human.
12:00Neuroscientists study the brain, determined to understand how neural processes create subjective experiences.
12:07And there are certain specific brain structures that are believed to be linked to conscious awareness.
12:12Examples are the prefrontal cortex, thalamus, and posterior cortex,
12:17which are all thought to play a crucial role in generating sentient experiences.
12:22Our neuroimaging techniques are only getting more advanced, allowing scientists to observe brain activity in real-time better than ever.
12:30And as this allows them to correlate specific brain patterns with conscious states, you might imagine that the case was closed.
12:37But it isn't.
12:38There's Global Workspace Theory, for example, which claims that our brains function more like a global workspace.
12:45According to GWT, the brain contains multiple, specialized processes, operating unconsciously and independently.
12:53They all handle various tasks like perception, memory, motor control, etc.
12:59But when information from these needs to be made available for cognitive functions, it enters the global workspace,
13:05which is something akin to a theatre, and it's only on this stage that the conscious mind is formed.
13:12Meanwhile, on the other side of the coin, there are theories that describe consciousness as something else entirely.
13:18As something that's not tied to or generated by any one person's physical brain at all.
13:23Models such as biocentrism claim that consciousness could instead be something like a universal energy,
13:29and that our brains and bodies only ever act as temporary hosts for it.
13:34There are huge implications for life after death here, but for now it goes to show just how tricky the problem of consciousness still is.
13:45Now we're also drawing upon the fields of philosophy and religion, as well as science.
13:50The concept of a soul is that it's the non-material essence that defines our personalities and consciousness.
13:57In most tellings, it's usually immortal and separate from our physical bodies.
14:02The existence of a soul is a key aspect to most major religions.
14:06In Christianity, it survives after death, where it enters the afterlife and is judged by God.
14:12In Hinduism and Buddhism, the soul undergoes a cycle of rebirth, entering a new life form post-death via reincarnation.
14:20Philosophically, the soul is an idea that's been explored for thousands of years.
14:25The Greek philosopher Plato, for instance, also believed it to be immortal, and that it existed before inhabiting a physical body.
14:33The 17th century's René Descartes, on the other hand, thought the soul resided in the pineal gland, a tiny organ in our brains.
14:41Meanwhile, in Japanese legend, the soul is contained in the shurikodama, which is a jewel hidden in our rear ends.
14:49So, all across human history, wildly different concepts of the soul have been conceived.
14:54From a scientific perspective, the soul's existence is entirely unproven, and completely beyond the scope of rigorous investigation.
15:02Again, neuroscience has made some great strides in understanding how our brains potentially create consciousness.
15:08And perhaps these advancements suggest what we consider to be the soul is actually entirely created by physical processes in the brain.
15:17There isn't a great deal of difference between the soul and general consciousness here, though, so science might be said to miss the mark.
15:24In fact, for some, the soul might forever be unprovable.
15:32Around 4.5 billion years ago, Earth was only just beginning to take shape.
15:36It was a hostile environment, dominated by scorching volcanic activity, a toxic atmosphere, and frequently devastating meteorite impacts.
15:45Despite this, it clearly had the essential ingredients needed for life.
15:50Water, organic molecules, and energy from sunlight.
15:53Many scientists believe that life formed here, in what's often termed to be a primordial soup.
15:59They think the simple organic compounds that existed at the start gradually evolved, getting more and more complicated, until eventually they spawned life as we know it.
16:09The Miller-Urey experiment was an attempt to verify this.
16:12Carried out in 1952, it simulated the conditions thought to be present in prebiotic Earth.
16:18And it worked.
16:19The experiment demonstrated that organic molecules like amino acids can form from simple inorganic compounds under such conditions.
16:28Amino acids are the building blocks of proteins, making them a vital foundation for life.
16:33So, the early fifties test could be said to have cracked the mystery.
16:38There is still work to be done, however.
16:40And there are still competing theories as to how the very first life-enabling substances arrived on our planet.
16:46There's always a little further back that we could go, and this is where science is today.
16:51One famous line of research takes us to the theory of panspermia, an increasing focus of astrobiology.
16:58Panspermia is the idea that life was initially delivered to Earth from outer space, carried here by a meteorite, comet, or asteroid.
17:06Studies of matter from space have found organic compounds such as amino acids to be present.
17:12This at least shows that the components for life are seemingly widespread across the cosmos.
17:17As to whether or not we really did begin off Earth rather than on it, it remains an open question.
17:24And the race is on to reach an answer.
17:26Number nine, are we alone?
17:29Panspermia takes us neatly to our penultimate problem, the potential for alien life.
17:35For one, there's directed panspermia, which is a more controversial offshoot of the theory,
17:40suggesting that not only did the base materials for life come from space, but they were also purposely sent here by intelligent beings.
17:48The jury's definitely still out on that one.
17:51But aliens in general are, today, far from controversial.
17:55We know that the solar system hasn't been around long compared to the rest of the universe
17:59It's only 4.5 billion years old, while the universe is at least 13.8 billion.
18:05We also know that there are billions of systems in the Milky Way with stars that are similar to our own,
18:11with a lot of these probably having planets that are very much like Earth.
18:15A lot of those planets could, even should, then be billions of years older than ours.
18:20So, statistically speaking, intelligent life should be extremely common in the universe.
18:25Not only this, but Earth should probably have already been visited by aliens at least once.
18:30And yet, all observations tell us this isn't the case.
18:34It's a famous quandary and discrepancy known as the Fermi Paradox.
18:38So, what's going on?
18:40Have we just not observed enough of the universe?
18:43Perhaps, but it seems unlikely.
18:45The Kepler Space Telescope alone has identified thousands of exoplanets, many with conditions similar to Earth.
18:52But, so far, none of these have shown obvious detectable signs of life.
18:56More broadly, the Search for Extraterrestrial Life, or SETI, is an organization founded primarily to detect alien signals.
19:04But no definitive signals have ever been detected.
19:07To coin another common term for scientists working in the field, we are in the mists of a Great Silence.
19:14One possible answer to the Fermi Paradox is the Great Filter.
19:18In short, this suggests that intelligent life always faces one obstacle so difficult that no, or extremely few, species can evolve past it.
19:27Maybe that's why there are no aliens to be found.
19:30Because they've all been killed off by whatever the filter is.
19:33The somewhat frightening implication, though, is that humanity should also pass through the same filter.
19:39And, currently, it's unclear if we've already done so.
19:42It's unknown whether the Great Filter is in front of us or behind us.
19:47Both options are rather bleak scenarios.
19:49If it's in front of us, then we might not be around for much longer.
19:53If it's behind us, then we likely are alone in the universe.
19:57For now, though, there's just no way to confirm one or the other.
20:02Number 10. Is there a god?
20:05Almost everyone on Earth holds at least an idea of what a god or the god is.
20:11Whether or not you believe, god is something that has seemingly spread through and shaped human history.
20:17For billions around the world, belief in a higher power is core to their faith.
20:21Most religions offer diverse perspectives on the nature of god.
20:25But, more often than not, gods are omnipotent and omniscient.
20:29Many are benevolent, and a select few are pitched as being the creator of all things.
20:34Sacred texts and the testimony of prophets are cited as evidence for them.
20:39But, of course, science needs a little more.
20:42Science, by its nature, doesn't address the supernatural.
20:45At its heart, it relies on empirical evidence and testable theories.
20:49It, therefore, doesn't have the tools to prove or disprove the existence of god.
20:54That said, science isn't inherently, inescapably atheist, either, as many may believe.
20:59For example, Einstein expressed a sense of wonder at the cosmos which he called a cosmic religious feeling.
21:06Carl Sagan famously spoke of a complex appreciation for some aspects of Hinduism.
21:11On the other hand, some religious individuals believe science to be a way to explain and appreciate god's work.
21:17So, there isn't always such a huge divide.
21:20In the words of the pioneering quantum physicist Max Planck,
21:24quote, science cannot solve the ultimate mystery of nature because we ourselves are part of the mystery that we are trying to solve.
21:31Somewhat appropriately, Planck's sentiments are open for interpretation.
21:35But with regards to god specifically, science can't answer to any particular aspect.
21:40It can only continue to unpick the mysteries of our world and reality as we live it here and now.
21:48What do you think? Is there anything we missed?
21:50Let us know in the comments, check out these other clips from Unveiled, and make sure you subscribe and ring the bell for our latest content.
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